A typical refrigerant based air-conditioning, refrigeration and heating system comprises a compressor and an associated condenser (or heat exchanger), which are used to convert low-pressure refrigerant vapor into high-pressure liquid refrigerant for cooling purposes. In this compression of vapor, a very large amount of heat is generated and this heat can be either dissipated externally to the space that will be cooled or used for heating in a reverse cycle system (also called a heat pump system). The high-pressure liquid refrigerant is then transported to an evaporator (or heat exchanger) and is allowed to decompress there back to a vapor. In this decompression phase change process, the evaporator/second heat exchanger temperature reduces significantly and the reduction in temperature is limited by a significant amount of heat which is absorbed from the air passing through the evaporator/second heat exchanger. The heat removed from the air passing through the evaporator/second heat exchanger produces a supply of very cold air into the room or area being cooled. A blower fan is used to drive air though the evaporator. The supply of low-pressure refrigerant is then returned to the compressor.
Air-conditioning, refrigeration and heating systems employing refrigerants can account for up to 60% of the energy demand in office and domestic/residential installations. However, despite recent technology improvements, refrigerant based systems have yet to benefit from a significant reduction in running costs and as a result this sector remains inefficient compared with other energy consuming areas. As an example, lighting typically accounts for only 10-20% of the total energy demand but recent energy reduction advances have reduced running costs by 80% or more compared with earlier designs.